Mendel

1
Mendels Laws

• Law of Independent Assortment allele pairs
  separate independently of one another during
  meiosis, therefore traits are inherited
  separately. (He discovered this using dihybrid
  crosses)
• Law of Segregation Organisms inherit one gene
  from each parent (a total of two copies).
  Organisms donate only one copy to their offspring
  (so the paired copy separates during gamete
  formation).

2
Most traits do not follow a simple dominance
pattern

• The Punnett Square was to show the probability of
  results from a simple dominance situation.
• Homologous chromosomes are the set of chromosomes
  donated by your parentsthe matching traits. One
  chromosome from your mom and one from dad.
• One of each from the set is what you donate to
  your child. (Fertilization)
• Fertilization is the fusing of haploid sex cells.

3
Heredity patterns can be calculated with
probability.

• Probability is the likelihood that something will
  happen.
• Probability predicts an average number of
  occurrences, not an exact number of occurrences.

• Probability applies to random events such as
  meiosis and fertilization.

4
KEY CONCEPT Independent assortment and crossing
over during meiosis result in genetic diversity.
5
Sexual reproduction creates unique combinations
of genes.

• Sexual reproduction creates unique combination of
  genes.
• independent assortment of chromosomes in meiosis
• random fertilization of gametes
• Unique phenotypes may give a reproductive
  advantage to some organisms.

6
Crossing over during meiosis increases genetic
diversity.

• Crossing over is the exchange of chromosome
  segments between homologous chromosomes.
• occurs during prophase I of meiosis I
• results in new combinations of genes

7

• Chromosomes contain many genes.

• The farther apart two genes are located on a
  chromosome, the more likely they are to be
  separated by crossing over.
• Genes located close together on a chromosome tend
  to be inherited together, which is called genetic
  linkage.
• Genetic linkage allows the distance between two
  genes to be calculated.

8
Genotype from phenotype?

• No you cannot determine genotype from phenotype,
  especially if the trait is more dominant.
• You could perform a testcross to determine an
  unknown organisms genotype.
• Testcross crossing an organism with an unknown
  genotype with an organism with a known phenotype
  to determine the genotype of the unknown
  organism.